The pH check on a thick sauce

Calibrate every session

Not at the start of the season. Meters drift and buffers age, and this is the measurement your whole regulatory position rests on. Fresh buffers, on a bench, before the readings that matter.

Why a thick product needs a dilution

A glass electrode needs liquid contact, and a paste does not give it one. The standard answer is to blend a weighed sample with an equal weight of distilled water and measure that, which gives a repeatable reading provided the ratio is always the same and always recorded. An undiluted reading taken by pushing a probe into a thick sauce is not wrong so much as not comparable to the next one.

Ask the process authority which method your filed process expects, because the dilution ratio is part of the procedure rather than a convenience.

Measure the finished product, settled and at room temperature

The number that counts is the equilibrium pH of the product, not the pH of the acid you added or of the batch mid-reduction. Temperature affects the reading, and a jar still equalizing is not the product yet.

Record it against the batch

The reading, the dilution, the date, the meter and the buffers, with the batch code beside them. That record is the evidence the process was followed, and it is what gets asked for rather than what you remember.

If it is out

The batch is not shelf stable, and that does not change because the next one was fine. Refrigerate it, sell it short-life, or discard it. Do not take repeated readings until one comes out where you want it.

References